Covalent Heterobivalent Inhibitor Design for Inhibition of IgE-Dependent Penicillin Allergy in a Murine Model

Abstract

Drug allergies occur when hapten-like drug metabolites conjugated to serum proteins, through their interactions with specific immunoglobulin E (IgE), trigger allergic reactions that can be life-threatening. A molecule termed covalent heterobivalent inhibitor (cHBI) was designed to specifically target drug-hapten specific IgE to prevent it from binding drug-haptenated serum proteins. cHBI binds the two independent sites on a drug-hapten specific antibody and covalently conjugates only to the specific IgE, permanently inhibiting it. The cHBI design was evaluated via ELISA to measure cHBI-IgE binding, degranulation assays of rat basophil leukemia (RBL) cells for in vitro efficacy, and mouse models of ear swelling and systemic anaphylaxis responses for in vivo efficacy. The cHBI design was evaluated using two seperate models: one specific to inhibit penicillin G reactive IgE, and another to inhibit IgE specific to a model compound, dansyl. We show that cHBI conjugated specifically to its target antibody and inhibited degranulation in cellular degranulation assays using RBL cells. Furthermore, cHBIs demonstrated in vivo inhibition of allergic responses in both murine models. We establish the cHBI design to be a versatile platform for inhibiting hapten/IgE interactions, which can potentially be applied to inhibit IgE mediated allergic reactions to any drug/small molecule allergy.